Don't discount C# and the .NET framework. I'm not an expert in the differences, just another coder, but there's been a lot of enhancements to C# .NET in the past couple of years.
It was very easy to develop, test and deploy. Npgsql has support for most of the postgres features (except complex types but that's planned).
I deployed everything on Ubuntu servers and runs like a champ. (I'm saying prototype and it is indeed, but it has 100-something users across the globe testing their workflows continuously and it has a lot of CPU-intensive stuff which is child's play with .NET to manage asynchronously. A production app would have two orders of magnitude more users but I think I'll be able to get away with a single server if it comes to that).
We had a couple experiments at my company but going from 1.0 to 1.1 had breaking changes so we couldn’t upgrade easily.
Can completely run on Linux and Kestrel (behind NGINX) is a very fast webserver. https://docs.microsoft.com/en-us/aspnet/core/publishing/linu...
Definitely microservice friendly. Azure is reasonably priced with various serverless offerings.
And you can just run .NET Core if you want to target Linux and pick a dirt cheap host.